1. Field of Invention
The present disclosure relates to an antenna structure, and more particularly to an asymmetrical dipole antenna applicable to different types of radio signal transmission.
2. Related Art
In current antenna structures, an omnidirectional antenna is very useful in various radio communication apparatuses since a radiation mode supports desirable transmission and reception effects in a mobile unit. In order to improve gain of the omnidirectional antenna and impedance matching of the antenna, mostly wide feed wires or loop circuits are used in the arrangement to design a radiation portion and a ground portion.
However, the use of a feed wire or a loop circuit has disadvantages. If a feed wire is too wide, the transmitted may affect the signal of the radiation portion and cause a coupling effect between the feed wire and the radiation portion. Moreover, the impedance matching of the antenna component is affected, and the width of a frequency band is limited. If spacing between the feed wire and the radiation portion is increased, the omnidirectional antenna's directivity in a certain direction easily becomes too high. On the other hand, although the loop circuit achieves high impedance, the manufacturing process is more difficult and thus the yield rate of the manufactured antenna is reduced.
Regardless of the type of antenna, as long as the antenna is disposed in a region with a physiographic barrier (such as a corner or a ceiling), gain values in specific directions are insufficient and poor communication quality occurs in signal reception and transmission. Therefore, the issue of how to reduce the complexity of manufacturing the antenna while maintaining or further improving the antenna gain is an issue that the manufacturers should pay attention to.